Stacked bus assembly with stepped profile

ABSTRACT

A bus bar assembly for a power distribution unit or other piece of electrical equipment includes a stack of bus bars configured to be attached to a surface and insulated from one another. The bus bars have aligned longitudinal centerlines and respective widths that decrease along a direction perpendicular to the surface to provide a stepped profile in cross-section. In some embodiments, the bus bars may have substantially the same cross-sectional area.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/451,997, filed Mar. 7, 2017, the content of which is herebyincorporated herein by reference in its entirety.

BACKGROUND

The inventive subject matter relates to electrical apparatus and, moreparticularly, to electrical apparatus including bus bars for connectionof electrical devices such as circuit breakers.

Electrical equipment, such as power distribution units (PDUs) andbreaker panels, often include bus bars that are used to provideconnections to devices such as circuit breakers, contactors, powerconverters and the like. For example, a typical three-phase PDU mayinclude three bus bars that are attached to a rear wall of the PDUcabinet or panel. In some conventional panel boards, such bus bars maybe commonly arranged in a vertical manner and spaced apart along ahorizontal direction, and circuit breakers may be connected to the busbars using wires or other connecting structures. Various other bus bararrangements for electrical panel boards are described, for example, in:U.S. Pat. Nos. 3,302,880; 3,346,777; 3,691,727; 3,721,864; 3,842,322;and 5,166,861.

SUMMARY

Some embodiments of the inventive subject matter provide a bus barassembly including a stack of bus bars configured to be attached to asurface and insulated from one another. The bus bars have alignedlongitudinal centerlines and respective widths that decrease along adirection perpendicular to the surface, such that the bus bars may forma stepped profile in cross-section. In some embodiments, the bus bars ofthe stack of bus bars may have substantially the same cross-sectionalarea, e.g., wider ones of the bus bars may be thinner than narrower onesof the bus bars.

In some embodiments, the stack of bus bars may include a first bus barhaving a first width, a second bus bar overlying the first bus bar andhaving a second width less than the first width, and a third bus baroverlying the second bus bar and having a third width less than thesecond width. The first, second and third bus bars may have conductorattachment portions proximate edges thereof. Conductor connection means,such as bolt holes, may be provided at the conductor attachmentportions. The second bus bar may be thicker than the first bus bar andthe third bus bar may be thicker than the second bus bar. The bus barsmay be separated from one another by spaced apart insulating standoffs.

Further embodiments provide an apparatus including an enclosure and astack of bus bars attached to a surface of the enclosure andelectrically insulated from one another, wherein the bus bars havealigned longitudinal centerlines and decreasing widths along a directionperpendicular to the surface of the enclosure and are configured to beelectrically connected to one or more electrical devices disposed in theenclosure via conductor members attached to conductor attachmentportions proximate edges of the bus bars.

Still further embodiments provide a power distribution unit including anenclosure, a stack of bus bars mounted on a surface within the enclosureand separated from one another by spaced apart insulating standoffmembers. The bus bars have aligned longitudinal centerlines and haverespective widths that decrease along a direction perpendicular to thesurface of the enclosure. The power distribution unit further includesat least one circuit breaker mounted in the enclosure and electricallyconnected to the bus bars by conductor members that are attached toconductor attachment portions of the bus bars proximate edges of the busbars.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a bus bar assembly according to someembodiments of the inventive subject matter.

FIG. 2 is a top view of the bus bar assembly of FIG. 1.

FIG. 3 is a side view of the bus bar assembly of FIG. 1.

FIG. 4 is a longitudinal cross-section view of the bus bar assembly ofFIG. 1.

FIG. 5 is a perspective view of a power distribution unit including thebus bar assembly of FIG. 1.

FIG. 6 is detailed view of the power distribution unit of FIG. 5.

DETAILED DESCRIPTION

Specific exemplary embodiments of the inventive subject matter now willbe described with reference to the accompanying drawings. This inventivesubject matter may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventivesubject matter to those skilled in the art. In the drawings, likenumbers refer to like items. It will be understood that when an item isreferred to as being “connected” or “coupled” to another item, it can bedirectly connected or coupled to the other item or intervening items maybe present. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventivesubject matter. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless expresslystated otherwise. It will be further understood that the terms“includes,” “comprises,” “including” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, items, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, items, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this inventive subject matterbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of thespecification and the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Embodiments herein relate to bus bar assemblies that have a compactstacked form factor that may be advantageously used in any of a varietyof different types of electrical equipment. According to someembodiments, a multi-phase (e.g., three phase) bus bar assembly includesa plurality of bus bars stacked with their longitudinal axes insubstantial alignment and electrically insulated from one another. Thebus bars have respective widths that decrease along a directionperpendicular to a surface (e.g., a rear wall) upon the bus bar assemblyis mounted, such that each bus bar is narrower than the immediatelyunderlying bus bar. In this manner, conductor attachment surfaces of thebus bars may be more easily accessed. Circuit breakers or other devicesmay be connected to these conductor attachment surfaces using, forexample, wires, conductive bars or other conductors that may be boltedor otherwise attached to the conductor attachment surfaces. The bus barsmay have different thicknesses such that cross-sectional areas of thebus bars may be substantially the same and thus provide substantiallysimilar current capacities.

FIGS. 1-4 illustrate a bus bar assembly 100 according to someembodiments of the inventive subject matter. The bus bar assembly 100includes stacked first, second and third bus bars 110, 120, 130, whichmay be formed, for example, of a conductive material, such as copper,aluminum or other conductive metals or alloys. The bus bars 110, 120,130 are mechanically interconnected and electrically insulated from oneanother by using insulating standoffs 150 that provide spacing betweenthe first and second bus bars 110, 120 and between the second and thirdbus bars 120, 130. Similar insulating standoffs 150 may be used to mountthe first bus bar 110 to a surface S, such as a wall or other surface ofan enclosure.

The bus bars 110, 120, 130 have respective widths W1, W2, W3 thatdecrease along a direction D perpendicular to the surface S to which thebus bar assembly 100 is mounted, such that the bus bar assembly 100provides a stepped profile in longitudinal cross section, as shown inFIG. 4. This arrangement exposes surfaces of conductor attachmentportions 110 a, 120 a, 130 a proximate respective edges of the bus bars110, 120, 130. Conductors (e.g., wires, conductive bars, etc.) can beconnected to these conductor attachment portions 110 a, 120 a, 130 ausing, for example, bolt holes 140 that are configured to receive boltsthat may be used to secure conductor terminals to the conductorattachment portions 110 a, 120 a, 130 a. It will be appreciated thatother means may be used to attach conductors to the bus bars 110, 120,130, such as studs that protrude from the conductor attachment portions110 a, 120 a, 130 a to enable fixation of terminal ends of wires orother conductors to the bus bars 110, 120, 130 using nuts, or clamps,stabs or similar terminations connected to ends of wires or otherconductors may be used to engage the edges of the bus bars 110, 120, 130to provide electrical coupling to the conductor attachment portions 110a, 120 a, 130 a.

In the illustrated embodiments as further shown in FIG. 4, the first,second and third bus bars 110, 120, 130 are flat bars with rectangularcross-sections. In the illustrated embodiments, the bus bars 110, 120,130 have respective different thicknesses T1, T2, T3, wherein the firstbus bar 110 is thinner than the second bus bar 120 and the second busbar 120 is thinner than the third bus bar 130, such that cross-sectionalareas of the bus bars 110, 120, 130 are substantially equal and thushave substantially equal current-carrying capability. However, it willbe appreciated that some embodiments may use bus bars with the samecross-sectional area, wherein this cross-sectional area is great enoughto support currents that any of the bars is expected to experience. Itwill be further appreciated that some embodiments may use bus bars thathave non-rectangular cross-sections.

According to some embodiments, a bus bar assembly along the lines of thebus bar assembly 100 of FIGS. 1-4 may be used in a PDU to enableconnection of circuit breakers or other devices to a three-phase powersource. Referring to FIGS. 5 and 6, a three-phase PDU 500 includes anenclosure 510. A surface 520 within the enclosure 510 has a bus barassembly 100 mounted thereon. Three-phase first circuit breakers 530have phase line inputs coupled to respective bus bars of the bus barassembly 100 using wires 540 having first terminals bolted to the busbars 110, 120, 130 of the bus bar assembly 100 and second terminalsbolted to the phase inputs of the first circuit breakers 530. It will beappreciated that connections other than bolted connections may be used,e.g., the wires 540 may be clamped at the phase inputs of the firstcircuit breakers 530 and/or at the bus bars 110, 120, 130. Three-phasesecond circuit breakers 550 have phases coupled to respective ones ofthe bus bars 110, 120, 130 using rigid connecting bar links 560 a, 560b, 560 c that bolt to the bus bar assembly 100 and the second circuitbreakers 550. As can be seen in FIG. 6, the connecting link bars 560 a,560 b, 560 c may have different lengths and bend locations toaccommodate the stepped positioning of the bus bars 110, 120, 130. Suchconnecting link bars 560 a, 560 b, 560 may be interchangeable to allowuser selectable phase interconnections. Connection arrangements such asthose shown in FIGS. 5 and 6 may also be used for devices that are onlyconnected to one or two phases.

It will be appreciated that, in some embodiments, similar bus bararrangements may include more or fewer bus bars. For example, a similararrangement of two stacked bus bars may be used for applications inwhich only two phases are needed (e.g., in residential panels). In otherembodiments, one or additional stacked bus bars may be added to provideneutral and/or grounding conductors. Some arrangements may use multiplebus bars per phase, e.g., a stacked bus bar assembly may include two busbars for each phase, arranged in a stepped manner.

Bus bar assemblies according to embodiments of the inventive subjectmatter may be advantageously used in PDUs and breaker panels as shown,for example, in FIGS. 5 and 6, but it will be appreciated that bus barassemblies according to some embodiments may be used in other types ofelectrical equipment. For example, bus bar assemblies according to someembodiments may also be used in motor drives, motor control centers,uninterruptible power supplies, and the like.

In the drawings and specification, there have been disclosed exemplaryembodiments of the inventive subject matter. Although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the inventive subject matterbeing defined by the following claims.

1. (canceled)
 2. A bus bar assembly comprising: a first bus bar, asecond bus bar partially overlapped by the first bus bar; and at leastone electrical connection on a portion of the second bus bar that is notoverlapped by the first bus bar.
 3. The bus bar assembly of claim 2,wherein the first and second bus bars comprise respective elongate firstand second flat bars arranged in parallel.
 4. The bus bar assembly ofclaim 3, wherein edges of the first and second flat bars are arranged ina stair stepped manner.
 5. The bus bar assembly of claim 3, whereinfirst edges of the first and second flat bars are arranged in a stairstepped manner on a first side of the bus bar assembly and whereinsecond edges of the first and second flat bars are arranged in a stairstepped manner on a second side of the bus bar assembly.
 6. The bus barassembly of claim 5, wherein the first and second flat bars havedifferent widths.
 7. The bus bar assembly of claim 5, wherein the firstand second flat bars have different thicknesses.
 8. The bus bar assemblyof claim 3, further comprising: a third bus bar comprising an elongatethird flat bar parallel to the first and second flat bars and partiallyoverlapped by the second flat bar; and at least one electricalconnection on a portion of the third flat bar that is not overlapped bythe second flat bar.
 9. The bus bar assembly of claim 8, wherein firstedges of the first, second, and third flat bars are arranged in a stairstepped manner on a first side of the bus bar assembly and whereinsecond edges of the first, second, and third flat bars are arranged in astair stepped manner on a second side of the bus bar assembly.
 10. Thebus bar assembly of claim 9, wherein the first, second, and third flatbars have different widths.
 11. The bus bar assembly of claim 9, whereinthe first, second, and third flat bars have different thicknesses. 12.The bus bar assembly of claim 8: wherein the at least one electricalconnection on a portion of the second bus bar that is not overlapped bythe first bus bar comprises a conductor fastened to the second bus barbetween an edge of the first bus bar and an edge of the second bus bar;and wherein the at least one electrical connection on a portion of thethird flat bar that is not overlapped by the second flat bar comprises aconductor fastened to the third bus bar between the edge of the secondbus bar and an edge of the third bus bar.
 13. The bus bar assembly ofclaim 2, wherein the at least one electrical connection comprises aconductor fastened to the portion of the second bus bar that is notoverlapped by the first bus bar.
 14. The bus bar assembly of claim 13,wherein the conductor is fastened to the second bus bar between an edgeof the first bus bar and an edge of the second bus bar.
 15. A bus barassembly comprising: a first bus bar; and a second bus bar parallel tothe first bus bar; and at least one electrical conductor fastened to thesecond bus bar between a lateral edge of the first bus bar and a lateraledge of the second bus bar.
 16. The bus bar assembly of claim 15,wherein longitudinal centerlines of the first and second bus bars arealigned.
 17. The bus bar assembly of claim 16, wherein the first andsecond bus bars comprise respective flat bars with different widths andwherein the at least one electrical conductor comprises a firstelectrical conductor fastened to the second bus bar on a first side ofthe first bus bar and second electrical conductor fastened to the secondbus bar on a second side of the first bus bar.
 18. The bus bar assemblyof claim 15, further comprising: a third bus bar parallel to the firstand second bus; and at least one electrical conductor fastened to thethird bus bar between a lateral edge of the second bus bar and a lateraledge of the third bus bar.
 19. The bus bar assembly of claim 18, whereinlongitudinal centerlines of the first, second and third bus bars arealigned.
 20. The bus bar assembly of claim 19, wherein the first, secondand third bus bars comprise respective flat bars with different widths,wherein the at least one electrical conductor fastened to the second busbar comprises a first electrical conductor fastened to the second busbar on a first side of the first bus bar and a second electricalconductor fastened to the second bus bar on a second side of the firstbus bar, and wherein the at least one electrical conductor fastened tothe third bus bar comprises a first electrical conductor fastened to thethird bus bar on a first side of the second bus bar and a secondelectrical conductor fastened to the third bus bar on a second side ofthe second bus bar.